In the field of medical imaging, prior to the digitization of medical imaging, medical-imaging users (e.g., Radiologists) would analyze physical film printed images in light boxes, and use physical devices such as magnifying glasses, rulers, grease pencils, and their hands to manipulate the physical printed medical images in order to interpret and diagnose the images. With the digitization of medical imaging, the physical film became a digital image, displayable on a computer monitor. A medical-imaging system became a computer application or collection of computer applications, which require a computer or computers to operate. At present, medical-imaging systems are interacted with through a mouse and keyboard. Commands to the medical-imaging system are typically invoked through mouse and/or keyboard interactions.
For image-intensive computing with rich graphical user interfaces, the mouse is showing its age. The mouse constrains the interaction to a single x, y point on the display with buttons to make selections and initiate modes of operation, such as click and drag. Most modern computer mice also have a special purpose scroll mechanism, often a wheel. Much of the human hand and finger capabilities and dexterity are not utilized with a mouse, and a mouse is limited to only one hand. Using the mouse for long periods of time tends to cause fatigue and repetitive stress symptoms due to the need to grasp the device and repeatedly perform small stressing motions of the fingers to click buttons.
For alphanumeric text entry, and initiating commands, keyboards have remained much the same for many decades and it has been difficult to find alternatives that perform better at text entry, for most users. When used as an input device for medical-imaging systems, some form of keyboard may remain in use for text entry for a long time to come. However, another common purpose for which keyboards are used with medical-imaging systems is for shortcuts to operations generally also available with the mouse but at the cost of navigation time and additional mouse clicking. The trade-off with mapping functions to keyboard shortcuts is the user has to learn and remember non-intuitive mappings of functions to keys, and most people have trouble remembering more than a few. In some cases, shortcuts to operations are also mapped to mouse modes of operation, often in conjunction with the keyboard. For example, a medical-imaging system zoom-image function could be mapped to the combination of holding down the Ctrl key and moving the mouse forward and back or rolling the scroll wheel. A better alternative to keyboard and mouse shortcuts for triggering medical-imaging system operations must make this mapping highly visible to reduce cognitive load, as well as make the interaction easy to reach quickly for efficiency.